The invention relates to a jump-starting arrangement for a motor vehicle, wherein the motor vehicle has an engine control unit and a starter for an internal-combustion engine. The motor vehicle is equipped with at least two partial onboard power systems, which are mutually coupled by way of at least one electric separator element. Each partial onboard power system is equipped with at least one rechargeable electric energy accumulator.
The onboard power system of motor vehicles is normally equipped with a starter battery in order to start the engine by means of a starter and to supply consuming devices with electric power in the event of a lack of coverage with electric power by the generator of the vehicle. The tasks of the starter battery therefore exceed the mere starting of the engine, so that, in the vehicle development, the starter battery is called an onboard power system battery or SLI battery, which stands for starting, lighting and ignition.
In the event of a battery failure or battery defect, the vehicle can be jump-started and/or the battery can be recharged. For the jump start as well as for the recharging, an external current and voltage source, such as a charging device or the onboard power battery of another vehicle (donor vehicle), is galvanically connected with that of the battery of the receiver vehicle. The electric connection is established by means of transfer cables. A transfer cable set consists of two insulated lines which are terminated by terminals or clips, which are designed for the size of the standard battery terminals (see, for example, Standard EN 50342-2 “Lead-Acid Starter Batteries. Dimensions of Batteries and Marking of Terminals” and Standard DIN 72553 “Jumper Cables for Road Vehicles with an Internal-Combustion Engine; Measurements, Requirements, Testing”). The positive line of the cable set connects the positive potentials, which means, for example, the two positive poles of the receiver and donor battery or the positive pole of the receiver battery with the positive output of a charging device. The negative line establishes a common ground. High currents flow in the case of a jump start (close to the kilo ampere range), so that the lines of the cable set have to have a correspondingly large line cross-section.
In many vehicle models, the battery terminals are not freely accessible, as, for example, when installed in the trunk. In this case, it is not the positive pole of the battery that is contacted but a terminal electrically connected with the positive line of the battery, thus, the line leading directly to the positive pole of the battery. This terminal is called a jump-starting base and is a connection identified in the vehicle and/or in the vehicle manual for the purpose of recharging and jump starting, and is easily accessible from the outside. It is usually situated in the area of the engine compartment and, after the opening of the hood, is easily accessible for connecting a charging clip. A jump-starting circuit, which is protected against a polarity reversal, for a vehicle having a starter battery is described in the state of the art, for example, in U.S. Pat. No. 6,211,577B1.
Modern motor vehicles with a voltage level of the onboard power system of 12V have an engine start-stop function, i.e. in suitable driving situations, the engine is switched off during the driving operation and is newly started after a brief time period. Examples where this occurs are waiting at a traffic light or at a railroad crossing. Preventing the engine from running saves fuel. Because the engine starts take place more frequently compared to vehicles without a start-stop function and because the electric consuming devices have to be supplied by way of the battery during the driving operation while the engine is switched off, the battery of the vehicle is in high demand. Vehicles with a start-stop function or vehicles with a high basic-current load, such as municipal or enforcement vehicles, are frequently equipped with a second onboard power system which has its own battery often called an additional-start battery. The partial onboard power system with the additional-start battery is separated from the partial onboard power system with the main battery, also called basic battery, by a battery separating relay and/or a DC converter. A function—and cost-optimized variant is the use of a unidirectional DC converter without a battery separating relay. The DC converter is electrically supplied by the partial onboard power system with the main battery and transmits electric power from the input-side basic onboard power system to the output-side additional-start onboard power system. Usually, the engine control unit is situated in the input-side onboard power system with the main battery, and the starter is situated in the output-side onboard power system with the additional-start battery. For a vehicle with two onboard power system batteries coupled by way of a DC converter, U.S. Pat. No. 6,396,240 B1 describes a jump-starting arrangement having a third battery.
It is an object of the invention to provide an improved jump-starting arrangement for a vehicle having at least two partial onboard power systems.
This and other objects are achieved by a jump-starting arrangement for a motor vehicle, wherein the motor vehicle has an engine control unit and a starter for an internal-combustion engine. The motor vehicle is equipped with at least two partial onboard power systems, which are mutually coupled by way of at least one electric separator element, and each partial onboard power system, respectively, is equipped with at least one rechargeable electric energy accumulator. At least two of the partial onboard power systems have a jump-starting base, and the jump-starting bases are galvanically separated from one another
According to the invention, at least two of the partial onboard power systems have a jump-starting base. The jump-starting bases are galvanically separated from one another.
It is an advantage of the invention that the energy accumulators in the respective onboard power systems are electrically accessible from the outside independently of one another. In each case, the external current and voltage supply of all energy accumulators takes place directly, i.e. no electric power drops out at the electric separating element.
According to an embodiment of the invention, the electric separating element is constructed as a DC converter and/or as a relay or as a switch. The generality will not be restricted if a DC converter is considered in the present specification.
According to an embodiment of the invention, the jump-starting bases can be contacted via an external current source by way of a cabled connection in order to charge the rechargeable electric energy accumulator.
This embodiment has the advantage that all energy accumulators can be charged rapidly, for example, in the case of a total discharge after being parked for a long time. The limitation of the electric power taken in by an electric energy accumulator takes place as a result of the recharging capacity of the energy accumulator or of the current-carrying capacity of the external current source at a defined charging voltage. The DC converter does not have a limiting effect.
The charge cable preferably has at least two parallel junctions in order to charge at least two of the energy accumulators with the same electric potential.
This embodiment has the special advantage that at least two energy accumulators can be charged by way of an external voltage source.
According to a further embodiment of the present invention, at least two of the partial onboard power systems are electrically connected by way of the jump-starting bases with an external current source in order to implement a jump start of the internal-combustion engine.
By way of this embodiment, the jump-starting capacity of the motor vehicle by use of an external voltage source is ensured, particularly in the event that all energy accumulators have been totally discharged, the engine control unit is electrically supplied in the partial onboard power system on the input side oriented toward the DC converter, and the starter of the vehicle is supplied in a second partial onboard power system oriented on the output side toward the DC converter.
The invention is based on the following considerations. Motor vehicles require an electric access to the starting and charging by way of an external voltage source or an external battery in emergency cases and when used at the dealer or factory within the scope of a jump-starting concept. Future hybrid and plug-in hybrid vehicles, and vehicles with an engine start-stop functionality, have several batteries with a voltage level of 12V. The basic onboard power system and the starter are supplied by separate batteries in separate onboard power systems. These onboard power systems are galvanically separated; the electric coupling usually takes place by way of a unidirectional DC converter, and in rarer cases, by way of a bidirectional DC converter. If necessary, the linking to the high-voltage onboard power system takes place by way of a further direct DC converter. In the case of a jump start, an electric access from the outside is to be provided such that a failure of the basic battery as well as of the starter battery is eliminated.
Currently, vehicles have a single jump-starting base. The external feeding of electric power into several onboard power systems with a voltage level of 12V, for example, the basic onboard power system and the additional-start onboard power system, can only be achieved insufficiently by means of the concept of a central jump-starting base.
A suitable measure is the introduction of a second jump-starting base; i.e. each battery in each partial onboard power system has a jump-starting base. In the case of, for example, two partial onboard power systems, the supplying of the partial onboard power systems can take place from the outside by use of a voltage source or external battery with a Y-shaped starter cable. The Y-shaping is exhibited by the fact that the positive line of the jump start cable, coming from the external source or battery, has a junction into an electric connection for each of the jump-starting bases. During a jump start, both onboard power systems of the vehicle to be supplied can simultaneously be supplied by way of a single positive jump-starting line, i.e. by way of a single external voltage source or external battery.
In the case of grounded partial onboard power systems, the connection of the ground points of the partial onboard power systems is not necessary and can take place by way of a conventional jump-starting ground cable with a branch to a central vehicle ground point.
In the case of partial onboard power systems separated from the ground, a jump-starting ground cable in a Y-shape is used analogous to the positive jump-starting line. This measure has several advantages. The jump-starting capacity of vehicles with separated starting onboard power systems is ensured. The energy supply of all partial onboard power systems is ensured during the installation in the production factory, when used at the dealer, for example, in the event of a repair, or during a recharging by the ultimate customer. This makes a considerable contribution to avoiding breakdowns and warranty costs.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.